Effects Of Orthokeratology Treatment On Ocular Surface And Tear Film In Myopic Adolescents

Objective To study the effects of the eye drops containing deproteinized calf blood extract on the ocular surface and tear film at the early stage after orthokeratology treatment in myopic adolescents;To objectively evaluate the changes of LLT and post-blink lipid layer dynamics in myopic adolescents after orthokeratology with LipiView ocular surface interferometer.Methods Fifty-nine myopes(118 eyes)who received vision correction by orthokeratology lens between June 2016 and October 2016 were included in this study.The subjects aged 12.11±2.51 years old,with mean spherical equivalent refraction-3.25±1.03 D at baseline.They were assigned randomly into two groups: the treatment group(29 cases,58 eyes)and the control group(30 cases,60 eyes).After lens delivery,the treatment group was given the eye drops containing deproteinized calf blood extract to presumably promote the repair of corneal epithelium,four times per day,while the control group was not given such eye drops.For each subject,measurements including the corneal topography,LLT,the tear film quality,tear film break-up time(BUT),fluorescein stain of corneal epithelium,and the ocular surface disease index(OSDI)were obtained at baseline,one week,and one month after lens delivery.Each eye of the 51 subjects(102 eyes)was assessed thrice by the investigator using LipiView ocular surface interferometer before orthokeratology treatment.Between every measurement,there was a 5-min interval for subject to rest.Then they were also measured on one month,three months,six months one year after lens delivery.The investigator were trained and validated for the use of the device.All measurements for each subject were performed on the same visit,in the same room with relatively unchanged conditions,namely room humidity,temperature and ambient lighting.The Ethics Committee of our hospital approved this study.All patients and their parents provided written informed consent for participation in the study and the use of their medical information for study analyses.The figures given by LipiView ocular surface interferometer were analyzing using custom programs written in MATLAB(MathWorks,Natick,MA).All statistical analyses were performed using commercially available statistical software(SPSS version 22,SPSS Inc.,Chicago,IL).Results are presented as means ± standard deviations.Testing for normal distribution was performed.For normally distributed values,independent sample t test was applied for analyzed the values between two groups;differences in data between baseline and follow-up visits were tested using analysis of variance or the paired t test.Statistical significance was defined as P< 0.05.The test-retest reproducibility was quantified with the intraclass correlation coefficient(ICC),with a value greater than 0.75 indicating good reliability.Results 1.Compared to the baseline,corneal curvature,SRI,BUT,OSI,and OSDI changed significantly after lens wearing(all P<0.05).These changes stabilized after one week.Lipid layer thickness showed no significant changes during the first month of orthokeratology treatment.Between the treatment group and the control group,there was no significant difference in corneal curvature,SRI,BUT,OSI,and OSDI at one-week and one-month visit(all P>0.05).The treatment group showed significantly lower rate of corneal staining which was mainly grade I,than the control group at one-week visit(10.3% vs.33.3%,P<0.05)and one-month visit(8.6% vs.26.7%,P<0.05).2.The interferometer showed good test-retest reproducibility,with an intraclass correlation coefficient(ICC)of 0.83.The LLT at baseline,one month,three months,six months,and one year after lens delivery were 58.30±16.28 nm,54.48±18.35 nm,56.30±22.81 nm,52.61±16.34 nm,56.45±17.33 nm.LLT showed no significant changes during the first year of orthokeratology treatment(P=0.628).After each blink,the LLT decreases by 16.03 nm on average and stabilized at 54.36 nm with a half-time of 0.68 s.After 1 year,the three numbers are 16.08 nm,56.40 nm,0.69 s.Conclusion Corneal curvature,SRI,BUT,OSI,rate of corneal staining and OSDI changed significantly after lens wearing.Eye drops containing deproteinized calf blood extract can protect and repair the corneal epithelium at the early stage of orthokeratology.LipiView ocular surface interferometer demonstrated good repeatability of the LLT measurement in myopia adolescents.LLT and post-blink lipid layer dynamics showed no significant changes during the first year of orthokeratology treatment.